Rockfire Resources PLC (LON:ROCK) shares jumped after it unearthed good grades of gold near the surface at a new area of its Plateau gold deposit in Queensland, Australia.

Drilling at a new breccia zone, where rocks are composed of broken fragments and had been missed by previous explorers, found six metres at 4.1 grammes of gold per tonne of rock (g/t Au) some 27 metres below the surface.

READ: Rockfire Resources hits gold across a 215 metre intercept in drilling at Plateau

This was within a broader interval of 16m at 1.7 g/t Au and not far from another area of 12m at 1.2 g/t Au at 12m depth.

Rockfire also encountered its highest gold grade so far at Plateau, with this newly identified zone including an intercept of 1m at 21.7 g/t.

This latest drilling, which was identified from fresh mapping and sampling by the company, is 120m east of drill hole BPL025 that had included 177m at 0.5 g/t and believed to be forming part of the same large gold system.

It has yet to be included in Rockfire’s maiden resource of 41,000 oz of gold estimated in July.

“Previous explorers had drilled nearby but missed the high-grade breccia,” said chief executive David Price. “We are starting to get a better understanding of the geology of this zone and the more we learn from each drill hole, the higher our drilling success rate becomes.”

He noted that the latest holes extend the mineralised target zone by another 120m towards the east: “It is our expectation that the geophysics recently completed at Plateau may highlight potential for a ‘sweet spot’ with higher average grades at depth.”

Rockfire is awaiting results from 11 more drill holes, a mix of resource infill and pure exploration holes at depths between 30m and 90m, while a geophysical survey designed to detect anomalies to depths of around 500m has also recently been completed at Plateau, with results currently being processed.

The shares leapt 43% to 1.95p, their highest level since July last year